The invention pertains to semiconductor processing, and in particular to a method and system providing a high flux of point of use activated reactive species for semiconductor processing.
Reactive species are employed in a number of important steps in the processing of semiconductor substrates. For example, reactive species may be employed for removing, or ashing the photoresist, and for etching of siliconiferous, metallic, or ceramic materials. It is known in the prior art to use a laser beam to selectively induce dissociation of a gaseous component to produce the desired gaseous reactive species for such semiconductor processing. Examples of such semiconductor processing systems are disclosed by the following references, which may be relevant to various aspects of the present invention.
U.S. Pat. No. 4,260,649 discloses providing a workpiece in a gaseous environment and a laser beam in close proximity and parallel to the surface of the workpieces in order to produce a gaseous reactant product for reaction with a surface of the workpiece.
U.S. Pat. No. 5,814,156 discloses providing a gaseous reactant in the vicinity of foreign material found on a surface of a substrate to form a non-solid by-product by delivering laser energy to the surface of the substrate to aid the gaseous reactant to react with the foreign material to form the non-solid by-product. The laser energy is arranged to be insufficient to damage the surface of the substrate.
Although the above-mentioned processing systems have been suitable for their intended purposes, one problem with these prior art systems is that they do not provide maximum laser beam energy at the point of use. Since activated gaseous reactive species have very short lifetime, it is therefore highly desirable to provide maximum laser beam energy at the point of use so that a high flux of activated reactive species is generated proximate to the surface of a workpiece.
The purpose of the present invention is to provide an improved method and system for chemical gas phase processing of workpieces and, more particularly to a method and system providing a high flux of point of use activated reactive species for semiconductor processing.
In one aspect, the invention encompasses a method of chemically treating a surface of a workpiece, comprising exposing the workpiece to a gaseous atmosphere containing a transmission gas that is substantially nonattenuating to preselected wavelengths of electromagnetic radiation. The method further comprises providing a flow of a gaseous constituent over the surface of the workpiece, and directing a beam of the electromagnetic radiation into the gaseous atmosphere. The beam converges in the flow in close proximity to the surface of the workpiece, but spaced a finite distance therefrom, to dissociate the gaseous constituent to produce a high flux of activated reactive species. The method further comprises reacting the activated reactive species with the surface of the workpiece.
In another aspect, the invention encompasses a system for chemically treating a surface of a workpiece comprising a supply of a transmission gas which is substantially nonattenuating to preselected wavelengths of electromagnetic radiation, and a supply of a gaseous constituent. The system further comprises a structure for exposing the workpiece to a controlled gaseous atmosphere containing said transmission gas and for providing a flow of said gaseous constituent to the surface of said workpiece. The system further comprises a radiation beam source adapted to converge in said flow in close proximity to the surface of the workpiece, but spaced a finite distance therefrom, to dissociate said gaseous constituent to produce a high flux of activated reactive species that chemically treat said surface of said workpiece.
These and other features and objects of the present invention will be apparent in light of the description of the invention embodied herein.